Generally, in a case in which a desired product is processed using machinery or equipment, horizontality of a reference element is very important. For machinery or equipment requiring precision, it is difficult to adjust vertical deflection and, in addition, considerable time is required.
A device for adjusting height and horizontal deflection to provide accurate horizontality is used in a variety of fields. One example of an application of such a device for adjusting height and horizontal deflection is in manufacture of cylindrical secondary batteries.
A cylindrical secondary battery is configured to have a structure in which an electrode assembly (jelly-roll) of a cathode/separator/anode structure is mounted in a cylindrical metal container. An exemplary vertical sectional view of the cylindrical secondary battery is shown in FIG. 1.
Referring to FIG. 1, a cylindrical battery 10 generally includes a cylindrical container 20, a jelly-roll type electrode assembly 30 mounted in the container 20, a cap assembly coupled to the upper part of the container 20, a beading part 21 for mounting the cap assembly 40, and a crimping unit 50 for sealing the battery.
The electrode assembly 30 is configured to have a structure in which a cathode 31 and an anode 32 are wound in a jelly-roll shape while a separator 33 is interposed between the cathode 31 and the anode 32. To the cathode 31 is attached a cathode tab 34, which is connected to the cap assembly 40. To the anode 32 is attached an anode tab (not shown), which is connected to the lower end of the container 20.
The cap assembly 40 includes a top cap 41 constituting a cathode terminal, a positive temperature coefficient (PTC) element 42 for intercepting electric current when the interior temperature of the battery is increased by detecting extreme increase in battery resistance, a safety vent 43 for intercepting electric current and/or exhaust gas when the interior pressure of the battery is increased, an insulating member 44 for electrically isolating the safety vent 43 from a cap plate 45 excluding a specific portion, and the cap plate 45, to which the cathode tab 34 coupled to the cathode 31 is connected. The cap assembly 40 is configured to have a structure in which the top cap 41, the PTC element 42, the safety vent 43, the insulating member 44, and the cap plate 45 are sequentially stacked. The cap assembly 40 is mounted on the beading part 21 formed internally by beading the upper end of the container 20 in a state in which a gasket 60 is mounted at the cap assembly.
In addition, such a cylindrical battery is manufactured by inserting a jelly-roll type electrode assembly into a cylindrical container, forming a beading part at a portion of the container corresponding to an upper end outer circumference of the jelly-roll type electrode assembly, mounting a cap assembly in which a gasket is disposed, and crimping the upper end of the container.
In a process of beading the upper end of the cylindrical container as described above, it is necessary to adjust the height of a worktable when a mold for the cylindrical battery is replaced such that height of the worktable is suited to the mold as needed. In addition, during a beading process, a beading knife approaches the cylindrical container from one side during the rotation of the cylindrical container to form an inwardly depressed beading part at the inside of the container. In a case in which horizontal deflection occurs, therefore, the beading part is not uniformly formed.
An exemplary structure of a conventional height adjusting device mainly used in a process of forming a beading part at such a cylindrical container is typically shown in FIG. 2.
Referring to FIG. 2, the height adjusting device 200 includes an upper plate 100, a lower plate 110, three posts 120, and fixing nuts 130 for fixing the posts 120 to the upper plate and the lower plate.
In the height adjusting device 200 of FIG. 2, however, it is not possible to check height deflection in real time when height deflection of the upper plate 100 is adjusted. In addition, during adjustment of the height deflection of the upper plate, it is necessary to frequently check the height of the upper plate 100. As a result, adjustment time is increased. Furthermore, the posts 1120 are individually adjusted.
In addition, adjustment of one post affects heights of other posts. In a case in which the posts 120 are fixed to the upper plate and the lower plate using the fixing nuts 130, heights of the posts 120 are irregularly changed with the result that it is not possible to achieve desired horizontality of the upper plate.
Consequently, there is a high necessity for a height adjustment device that is capable of fundamentally solving the above problems.